1. Field of the Invention
The present invention relates to novel 2-pyridyl-tiazolidin-4-one derivatives which shown excellent antagonisms to the platelet activating factor (hereinafter abbreviated as PAF).
2. Description of the Prior Art
PAF is a factor which in minute amounts can activate rabbit blood platelets. This factor was found in the supernatant of a culture of antigen-stimulated basophils of IgE-sensitized rabbits [Benveniate, J. et al J.P. Med., 136, 1356-1377 (1972)]. PAF is autocoid present in living bodies which has been identified as acetyl glyceryl ether phosphorylcholine (AGEPC), i.e. 1-O-hexadecyl/octadecyl-2-o-acetyl-sn-glyceryl-3-phosphorylcholine [Hanahan, D. J. et al., J. Biol. Chem, 254, 9355-9385 (1979)].
It is known that in addition to the platelet activation, PAF in extremely low concentrations exhibits various physiological actions, e.g. the depression of blood pressure, increase in vascular permeability, contraction of smooth muscle, activations of leucocyte-, monocyte, and macrophage, and acceleration of liver glycogen decomposition.
These physiological actions are regarded as being associated with a number of diseases, e.g. various kinds of inflammation, allergic diseases, circulatory diseases, and gastrointestinal diseases. Accordingly, the search of PAF-antagonists has been focused and energetically conducted in recent years for the purpose of preventing and/or treating these PAF-induced diseases.
However, while several compounds have been tested up to now to treat or prevent PAF-induced diseases, their effectiveness are not fully satisfactory.
On the other hand, a great number of studies are reported which relate to thiagolidin-4-one derivatives. Of these studies, however, those relating to 2-pyridylthiazolidin-4-one derivatives are reported only by the following seven documents: Japanese Patent Application Kokai (Laid-Open) No. 145670/79 discloses N-(substituted or unsubstituted phenyl and pyridyl) derivatives of 2-pyridylthiazolidin-4-one which are useful as agricultural chemicals. Japanese Patent Application Kokai No. 55184/80 discloses compounds including chiefly N-(substituted or unsubstituted phenyl, benzyl, and cycloalkyl) derivatives of 2-pyridylthiazolidin-4-one which are useful as agricultural chemicals. Japanese Patent Application Kokai Nos. 85380/82 and 88170/82 discloses the N-carboxycyclohexylmethyl derivatives of 2-pyridylthazolidin-4-one and the N-carboxymethylphenyl derivatives of the same compounds respectively, the former having an anti-complementary activity and the latter having antiinflammatory, analgesic, and antirheumatic activities. Japanese Patent Application Kokai No. 183689/83 discloses the N-pyrazinyl derivative of 2-pyridylthiazolidin-4-one useful as an agricultural chemical. U.S. Pat. No. 4,501,746 discloses N-(substituted phenyl) derivatives of 2-pyridylthiazolidin-4-one which are useful as intermediates in syntheses. Further, Japanese Patent Application Kokai No. 103881/86 disclosed N-(substituted carbamoyloxy) derivatives of 2-pyridylthazolidin-4-one which are useful as cardiotonica.